I have been a vegetarian for more than ten years. No meat, chicken, or fish. I do eat eggs and dairy, but as I have become a better eater, have reduced that too.
Concentrate on whole grains, fruits, and veggies. The key is variety. I don't look at the nutritional value of each meal, but of the day as a whole. If I am eating lunch out with co-workers I may wind up with a cheese sandwich - just make up the difference at dinner. I also took to grazing (on HEALTHY foods) rather than eating big meals.
There's a great book - Vegetarian Sports Nutrition by D. Enette Larson-Meyer, who is a cyclist. She covers foods as well as meeting the hydration needs. Great resource.